A probe, which will examine military personnel policies and the stress on healthcare workers, seeks to find any 'internal weaknesses or procedural shortcomings.'

Reporting from Washington — A wide-ranging review ordered Thursday by Defense Secretary Robert M. Gates will strive to answer what he called "troubling questions" raised by the shootings at Ft. Hood, Texas.

The Pentagon inquiry will be conducted alongside a government-wide review ordered by President Obama to examine the intelligence failures before the Nov. 5 rampage. Army Maj. Nidal Malik Hasan, a psychiatrist, stands accused of killing 13 people.

Gates expressed horror at the attack, saying there was little the department could do to ease the pain of the family members of those killed.

"All that is left for us to do is everything in our power to prevent similar tragedies from occurring in the future," Gates said.

The announcement of the Pentagon review came as the Senate Homeland Security and Governmental Affairs Committee began its probe into whether intelligence, military and law enforcement officials had missed important clues in relation to Hasan's being a possible threat.

Hasan had received repeated warnings about his poor work at Walter Reed Army Medical Center. He also was admonished for proselytizing after pressing others to accept his view of Islam.

In the aftermath of the shootings, former co-workers and documents have suggested that Hasan had evolved into a troubled Islamic extremist who investigators knew was in e-mail contact with a radical Yemeni American cleric.

Frances Fragos Townsend, a counter-terrorism official under former President George W. Bush, told the Senate panel that "systemic weaknesses" and failures had allowed Hasan to remain free. Another expert, retired Gen. John Keane, a former Army vice chief of staff, said the military needed "clear, specific guidelines" on what constitutes Islamist extremist behavior.

During a Pentagon news briefing, Gates avoided judgments on what may have gone wrong. But the 45-day Pentagon review will focus on several areas where the military has been criticized in the wake of the Ft. Hood attack.

Gates said the probe would examine procedures for identifying personnel who pose a potential threat to others, evaluate security on domestic military bases and assess emergency response capabilities. The review also will examine personnel policies, including discharge procedures, health assessment programs, counseling sessions and how the military handles "adverse" information about its service members.

The Pentagon investigation will be led by Togo West, a former Army secretary, and retired Adm. Vernon Clark, the former chief of naval operations.

The Defense Department will participate in the broader federal review, but Gates said a separate military probe was needed as well.

"It is prudent to determine immediately whether there are internal weaknesses or procedural shortcomings in the department that could make us vulnerable in the future," Gates said.

In launching the review, Gates adhered to his practice of appointing former Defense officials to investigate any military shortcomings. Most recently, he tapped a former Defense secretary, James Schlesinger, to lead a panel on the military's failure to properly track and secure nuclear-related material.

Each military branch will appoint officials to work with Clark and West. Gates said the Army's investigation would be more in-depth on whether procedures could have prevented the shootings.

"All of the services potentially have some of the same problems the Army is trying to deal with," Gates said. Initial results will help shape a follow-up probe, he said.

Gates said the investigations would also look at the stress on healthcare workers and the shortage of mental health professionals in the military.

"You go to the hospitals and you talk to the nurses and the doctors and those who care for these grievously wounded young men and women. . . and I can't imagine the burden on them of doing that all day every day," Gates said.

"How are we helping them deal with stress?" he added.

Sen. Joe Lieberman (I-Conn.), chairman of the Homeland Security committee, has called the Ft. Hood shootings an act of terrorism.

Asked whether he shared that view, Gates demurred. "I'm just not going to go there," he said, seeking to avoid prejudicing ongoing investigations.